多ID映射抛出BaseEntity

Question

我正在通过Hibernate映射类，我需要为Relationship映射多个ID。所有ID都是从BaseEntity扩展来的。如何为Relationship实现多个ID映射，其中包含User在DataBase中的外键？

基本字段userIdOne和userIdTwo在Relationship中必须包含用户发送请求的id。

User从BaseEntity扩展自己的ID。

每次我运行它时-获取错误：

这个类com.mylov.springsocialnetwork.model.Relationship不定义IdClass

    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @MappedSuperclass
    @EqualsAndHashCode
    public class BaseEntity implements Serializable {
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long id;

    }


    @Builder
    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @EqualsAndHashCode(exclude = {"posts"}, callSuper = false)
    @Entity
    public class User extends BaseEntity {
        private String userName;
        private String realName;
        private String email;
        private String phoneNumber;
        private LocalDate birthDate;

        @OneToMany(cascade = CascadeType.ALL, mappedBy = "userPosted")
        private Set<Post> posts = new HashSet<>();
        private String password;

        public User(Long id, String userName, String realName, String email, String phoneNumber, LocalDate birthDate,
                    Set<Post> posts, String password) {
            super(id);
            this.userName = userName;
            this.realName = realName;
            this.email = email;
            this.phoneNumber = phoneNumber;
            this.birthDate = birthDate;
            this.posts = posts;
            this.password = password;
        }
    }


    @Builder
    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @Entity
    public class Relationship implements Serializable {

        //@Id not working
        private Long userIdFrom;
        //@Id
        private Long userIdTo;

        @Enumerated(value = EnumType.STRING)
        private RelationshipStatus status;
        private LocalDate friendsRequestDate;
    }

Answer 1

您似乎希望在两个不同的用户之间建立一个Relationship。这意味着每个Relationship都是自己的对象/实体，并且应该有自己的@Id (与用户ID无关)。应该将构成此User的每个Relationship的链接映射为外键(可能是@ManyToOne和@JoinColumn)。

例如：

@Entity
public class Relationship implements Serializable {

    @Id
    private Long relationshipId;

    @ManyToOne(...)
    @ForeignKey(name="FK_USER_ONE") //for generation only, it isn't strictly required
    @JoinColumn(name="from")
    private Long userIdFrom;

    @ManyToOne(...)
    @ForeignKey(name="FK_USER_TWO") //for generation only, it isn't strictly required
    @JoinColumn(name="to")
    private Long userIdTo;

    @Enumerated(value = EnumType.STRING)
    private RelationshipStatus status;
    private LocalDate friendsRequestDate;
}

编辑:它不需要指定@ForeignKey注释。如果数据库表是自动生成的(可以用于测试，但通常不是生产中您想要的东西)，并且相应地在表上创建FOREIGN KEY约束，那么它们将被使用，但是JPA映射在没有它的情况下会很好地工作，因为它从您定义的模型中获取关系，而不是从数据库本身。